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Yard and Garden: Adjust Your Fall Lawn Care

AMES, Iowa — Fall lawn care is extremely important every year. This year, lawn dormancy needs to be considered before completing important fall chores that include mowing, fertilization, weed control and aeration, according to horticulturists with Iowa State University Extension and Outreach Hortline. Proper lawn care in the fall helps maintain a healthy, vigorous lawn and can revive a declining lawn.

Would it harm the turfgrass to fertilize the lawn when it’s dormant?

Fertilizing a dormant lawn will not harm it. However, the turfgrass may not receive the full benefit of the fertilizer application. If a granular fertilizer remains on the soil surface because of a lack of rain, some of the material may actually volatilize into the air. It would be best to wait until the weather pattern changes and it begins to rain before fertilizing the lawn. Fertilizer applications can be made anytime in September. Late October and early November also are excellent times to fertilize lawns.

Are broadleaf herbicides effective when applied during dry weather?

Broadleaf herbicides are most effective when applied to actively growing weeds. In non-irrigated lawns, some broadleaf weeds may become semi-dormant (their leaves curling up or wilting) during prolonged dry periods. An application of a broadleaf herbicide to drought stressed weeds will likely be less effective as the weeds may not absorb adequate amounts of the herbicide.

Fortunately, broadleaf herbicides can be effectively applied from late September to early November in Iowa. Home gardeners should wait until the area receives a good rain before applying a broadleaf herbicide to their lawn. Rainfall amounts of one-half inch or more should revive most broadleaf weeds.

Can I aerate a dormant lawn?

It’s advisable not to core aerate a dormant lawn. The aerifier’s metal tubes or tines will have difficulty penetrating the hard, dry soil. More importantly, core aerating a dormant lawn may harm the grass if the lawn doesn’t receive water (either from rain or irrigation) shortly thereafter.

It’s best to wait until the dormant lawn begins to green back up (when rains begin to fall or after initiating a watering program) before core aerating the lawn. Spring and late summer/early fall are the best times to core aerate home lawns in Iowa.